Formulations of bendamustine

ABSTRACT

Long term storage stable bendamustine-containing compositions are disclosed. The compositions can include bendamustine or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable fluid which can include in some embodiments PEG, PG or mixtures thereof and an antioxidant or chloride ion source. The bendamustine-containing compositions have less than about 5% total impurities, on a normalized peak area response (“PAR”) basis as determined by high performance liquid chromatography (“HPLC”) at a wavelength of 223 nm, after at least about 15 months of storage at a temperature of from about 5° C. to about 25° C.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 16/015,656,filed Jun. 22, 2018, which is a continuation of application Ser. No.15/432,335, filed Feb. 14, 2017, now U.S. Pat. No. 10,010,533, issuedJul. 3, 2018, which is a continuation of application Ser. No.15/013,436, filed Feb. 2, 2016, now U.S. Pat. No. 9,572,797, issued Feb.21, 2017, which is a continuation of application Ser. No. 14/031,879,filed Sep. 19, 2013, now U.S. Pat. No. 9,265,831, issued Feb. 23, 2016,which is a continuation of application Ser. No. 13/016,473, filed Jan.28, 2011, now U.S. Pat. No. 8,609,707, issued Dec. 17, 2013, whichclaims the benefit of U.S. Provisional Patent Application No.61/299,100, filed Jan. 28, 2010, the contents of each of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

Bendamustine free base is represented by the following structuralformula (I)

Bendamustine is used in the treatment of a number of cancers includingleukemias, Hodgkins disease and multiple myelomas. Bendamustine is theactive ingredient of the commercial product Treanda™, a lyophilizedpowder for reconstitution.

Bendamustine exhibits rapid degradation upon reconstitution of thelyophilized product. Bendamustine undergoes hydrolysis by directsubstitution rather than an addition elimination process due to thepresence of the highly labile aliphatic chlorine atoms. Some of the maindegradants of bendamustine are the monohydroxy compound known as HP1(hydrolysis product 1) and dihydroxy compound HP2 (hydrolysis product2). The monohydroxy compound appears as the main impurity at RelativeRetention Time (RRT) 0.6 and the dihydroxy compound appears as the mainimpurity at RRT 0.27. Minor peaks appear at RRT 1.2, which are presentlyunknown.

The stability of bendamustine in water is measured in hours, and istherefore, not suitable for long-term storage in liquid form. Thelyophile possesses good chemical stability. However, reconstitution ofthe lyophile is clinically inconvenient, taking 15-30 mins withimplications of chemical instability. There is a need for ready to use(RTU) bendamustine formulations having enhanced stability.

SUMMARY OF THE INVENTION

In other aspects of the invention, the bendamustine-containingcompositions include a) a pharmaceutically acceptable fluid whichcontains one or more of propylene glycol, ethanol, polyethylene glycol,benzyl alcohol and glycofurol, and b) a stabilizing amount of a chloridesalt. In other aspects of the invention, the bendamustine-containingcompositions include DMSO (dimethyl sulfoxide) as part of thepharmaceutically acceptable fluid included therein. Regardless of thepharmaceutically acceptable fluid included, the amount of bendamustineincluded in the composition is preferably from about 20 mg/mL to about60 mg/mL. Still further aspects of the invention include methods oftreatment using bendamustine-containing compositions and kits containingthe same.

One of the advantages of the inventive liquid compositions is that theyhave substantially improved long term stability when compared tocurrently available formulations. For example, the inventivebendamustine compositions are substantially free of impurities after atleast about 15 months at a temperature of from about 5° C. to about 25°C. The inventive formulations are advantageously ready to use or readyfor further dilution. Reconstitution of lyophilized powders is notrequired.

DETAILED DESCRIPTION OF THE INVENTION

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of ordinary skillin the art to which this invention belongs. In the event that there is aplurality of definitions for a term herein, those in this sectionprevail unless stated otherwise.

As used herein, RRT is calculated by dividing the retention time of thepeak of interest by the retention time of the main peak. Any peak withan RRT<1 elutes before the main peak, and any peak with an RRT>1 elutesafter the main peak.

For purposes of the present invention, “substantially free ofimpurities” shall be understood to include bendamustine-containingcompositions in which the amount of total impurities is less than about5%, as calculated on a normalized peak area response (“PAR”) basis asdetermined by high performance liquid chromatography (“HPLC”) at awavelength of 223 nm, after a period of about 15 months at a temperatureof from about 5° C. to about 25° C. The amount of impurities is furthercalculated as being based upon the original amount bendamustine (or saltthereof) being present in the composition or formulation.

For purposes of the present invention, a pharmaceutically acceptablefluid is a fluid which is suitable for pharmaceutical use.

Preferably, the amount of any individual degradant in the inventivecompositions does not exceed 2% PAR as determined by HPLC at awavelength of 223 nm after storage periods of at least about 15 monthsat a temperature of from about 5° C. to about 25° C. In some aspects,the amount of time the inventive compositions demonstrate long termstorage stability is at least about 18 months and preferably at leastabout 2 years when stored under the conditions described herein.

In accordance with one aspect of the invention there are provided longterm storage stable bendamustine-containing compositions including:

-   -   a) bendamustine or a pharmaceutically acceptable salt thereof;        and    -   b) a pharmaceutically acceptable fluid including        -   i) PEG, PG or mixtures thereof; and        -   ii) a stabilizing amount of an antioxidant.

The total impurities in the inventive compositions resulting from thedegradation of the bendamustine in the compositions is less than about5% PAR as determined by HPLC at a wavelength of 223 nm after at leastabout 15 months at a temperature of from about 5° C. to about 25° C.,and thus have long term stability for at least the same period of timeor longer. Preferably, the bendamustine-containing compositionsdemonstrate long term storage stability for at least about 2 years,especially when stored at the lower (refrigerated) temperatures. In oneembodiment, the amount of total impurities in the inventive compositionsresulting from the degradation of the bendamustine is less than about 3%PAR as determined by HPLC at a wavelength of 223 nm after at least about2 years at a temperature of from about 5° C. to about 25° C.

In some aspects of the invention, the bendamustine concentration in theinventive compositions is from about 10 mg/mL to about 100 mg/mL,preferably 20 mg/mL to about 60 mg/mL. Preferably the bendamustineconcentration in the inventive compositions is from about 25 mg/mL toabout 50 mg/mL, and more preferably from about 30 mg/mL to about 50mg/mL. It will be understood that compositions containing any usefulconcentration within the ranges, i.e. 10, 20, 25, 30, 35, 40, 45, 50,55, 60 . . . 100 are contemplated. In other embodiments, thebendamustine concentration in the composition is about 50 mg/mL. Inalternative aspects, the amount of bendamustine is outside these rangesbut the amounts will be sufficient for single or multipleadministrations of dosages generally regarded as effective amounts.

In several embodiments of the invention, pharmaceutically acceptablefluid is non-aqueous and may be, but is not necessarily, a solvent forthe bendamustine or salt thereof. Within this aspect, thepharmaceutically acceptable fluid is propylene glycol (PG) orpolyethylene glycol (PEG). In other embodiments of the inventionhowever, the pharmaceutically acceptable fluid is a mixture of PEG andPG. For example, the pharmaceutically acceptable fluid can include about50% PEG and about 50% PG. Alternatively, pharmaceutically acceptablefluid includes about 95% PEG and about 5% PG. The amount of PEG and PGcan also be varied within the ranges, i.e. the ratio of PEG:PG in thepharmaceutically acceptable fluid can range from about 95:5 to about50:50. Within this range, is a pharmaceutically acceptable fluidcontaining about 75% PEG and about 25% PG, and preferably 80% PEG and20% PG. In another embodiment, a pharmaceutically acceptable fluid caninclude about 85% PEG and about 15% PG while another preferredpharmaceutically acceptable fluid includes about 90% PEG and about 10%PG. The molecular weight of the PEG will be within the range ofpharmaceutically acceptable weights although PEG 400 is preferred inmany aspects of the invention.

Without meaning to be bound by any theory or hypothesis, the hydroxideof the polyethylene glycol molecule is less reactive than the hydroxidesof propylene glycol. As a result, the ester forms at a slower rate inpolyethylene glycol than propylene glycol and the resulting bendamustinedegradants are unexpectedly and substantially reduced over extendedperiods of time when PEG is a substantial part of the pharmaceuticallyacceptable fluid.

The bendamustine-containing compositions according to several preferredaspects of the invention include a stabilizing amount of an antioxidant.For purposes of the present invention, “stabilizing amount” shall beunderstood to include those amounts which increase or enhance thestability of the bendamustine in the compositions described herein. Thepresence of one or more antioxidants described herein thus contributes,at least in part to the long term stability of the composition. Withinthis guideline, suitable antioxidant concentrations in the compositionscan range from about 2.5 mg/mL to about 35 mg/mL, and preferably fromabout 5 mg/mL to about 20 mg/mL or from about 10 mg/mL to about 15mg/mL. In some other embodiments, the concentration of the antioxidantin the bendamustine-containing composition is about 5 mg/mL.

Suitable antioxidants for inclusion include those which arepharmaceutically acceptable for use in human and veterinary formulationsalthough not limited to those currently regarded as safe by anyregulatory authority. For example, the antioxidant can be selected fromamong lipoic acid, thioglycerol (also known as monothioglycerol) andanalogs thereof, propyl gallate, methionine, cysteine, metabisulfites,sodium formaldehyde sulfoxylate, phenol-containing aromatic andaliphatic compounds, dihydrolipoic acid and mixtures of the foregoing.Preferably, the antioxidant is thioglycerol, lipoic acid or a mixturethereof. Some particularly preferred embodiments of the inventioninclude thioglycerol.

In view of the foregoing, some preferred long term storage stablebendamustine-containing compositions in accordance with the inventioncompositions include:

-   -   I. a) bendamustine or a pharmaceutically acceptable salt        thereof; and        -   b) a pharmaceutically acceptable fluid including            -   i) polyethylene glycol and propylene glycol; and            -   ii) a stabilizing amount of thioglycerol; or    -   II. a) about 50 mg/mL bendamustine or a pharmaceutically        acceptable salt thereof; and        -   b) a pharmaceutically acceptable fluid including            -   i) about 90% PEG and about 10% PG; and            -   ii) about 2.5 mg/mL thioglycerol.                Each of these compositions have the same stability                profiles already described, i.e. having less than about                5% total impurities, PAR as determined by HPLC at a                wavelength of 223 nm, after at least about 15 months of                storage at a temperature of from about 5° C. to about                25° C.

In accordance with other aspects of the invention, there are providedlong term storage stable bendamustine-containing compositions,including:

a) bendamustine or a pharmaceutically acceptable salt thereof;

b) a pharmaceutically acceptable fluid including one or more of thefollowing: PG, ethanol, PEG, benzyl alcohol and glycofurol; and

c) a stabilizing amount of a chloride salt.

These compositions also have the low levels of impurities and long termstability mentioned herein. Preferred pharmaceutically acceptable fluidsinclude PG, PEG or ethanol in this embodiment of the invention.Preferably, the PEG is PEG 400. If desired, glycerin and/or 88% (w/w)lactic acid can be added to the pharmaceutically acceptable fluid.

Suitable chloride salts include but are not limited to organic chloridesalts, sodium chloride, choline chloride, hydrochloride salts of aminoacids and mixtures thereof. Thus, as will be appreciated by those ofordinary skill, one can select from among a number of suitable chloridesalts and it is Applicants' intention that the scope of the inventionincludes all such chloride salts that are capable of being included inbendamustine-containing formulations for extended periods without havinga deleterious effect on the drug. In one embodiment of the invention,the chloride salt concentration is from about 10 to about 300 mg/mL. Inanother embodiment, the chloride salt concentration is from about 50 toabout 215 mg/mL. In one preferred embodiment, the chloride saltconcentration is about 215 mg/mL.

In accordance with another aspect of the invention, there is providedlong term storage stable bendamustine-containing compositions,including:

-   -   a) bendamustine or a pharmaceutically acceptable salt thereof;        and    -   b) a pharmaceutically acceptable fluid including DMSO.

These compositions also have the low levels of impurities and long termstability mentioned herein. In some aspects, the bendamustineconcentration in these compositions is from about 10 mg/mL to about 100mg/mL. Preferably, the bendamustine concentration is from about 20 mg/mLto about 50 mg/mL, more preferably from about 25 mg/mL to about 50mg/mL. In an alternative embodiment, the bendamustine concentration isabout 50 mg/mL.

Another embodiment of the invention provides methods of treating cancerin mammals. The methods include administering to a mammal in needthereof an effective amount of one of the bendamustine-containingcompositions described herein. Since the active ingredient portion ofthe inventive composition is an FDA-approved drug, those of ordinaryskill will recognize that the doses of bendamustine employed in thisaspect of the invention will be similar to those employed in anytreatment regimens designed for bendamustine as marketed under the tradename TREANDA. The patient package insert containing dosing informationis incorporated herein by reference. The methods of treatment alsoinclude administering the inventive formulations for any purpose orphysical condition for which bendamustine has been indicated as beinguseful.

Another embodiment of the invention includes methods of preparingbendamustine-containing compositions described herein. The methodsinclude reconstituting lyophilized bendamustine in a pharmaceuticallyacceptable fluid containing one of the following:

-   -   A) i) PEG, PG or mixtures thereof; and        -   ii) a stabilizing amount of an antioxidant;    -   B) i) one or more of PG, ethanol, PEG, benzyl alcohol and        glycofurol; and        -   ii) a stabilizing amount of a chloride salt; or    -   C) DMSO.

The steps are carried out under pharmaceutically acceptable conditionsfor sterility and manufacturing.

In a further aspect of the invention, there are provided methods ofcontrolling or preventing the formation of impurities inbendamustine-containing compositions during long term storage. Themethods include combining an amount of bendamustine or apharmaceutically acceptable salt thereof with a sufficient amount of apharmaceutically acceptable fluid containing one of the following:

-   -   A) i) PEG, PG or mixtures thereof; and        -   ii) a stabilizing amount of an antioxidant;    -   B) i) one or more of PG, ethanol, PEG, glycofurol and benzyl        alcohol; and        -   ii) a stabilizing amount of a chloride salt; or    -   C) DMSO.

Further optional steps in accordance therewith include transferring oneor more pharmaceutically acceptable doses of the formulations into asuitable sealable container and storing the sealed container at atemperature of from about 5° C. to about 25° C. As a result of carryingout these steps, it is possible to control or substantially prevent theformation of impurities which otherwise occur withbendamustine-containing compositions during long term storage so thatthe artisan is provided with bendamustine-containing formulations havingless than about 5% total impurities PAR as determined by HPLC at awavelength of 223 nm, after at least about 15 months of storage at atemperature of from about 5° C. to about 25° C.

The compositions of the present invention can be packaged in anysuitable sterile vial or container fit for the sterile storage of apharmaceutical such as bendamustine. Suitable containers can be glassvials, polypropylene or polyethylene vials or other special purposecontainers and be of a size sufficient to hold one or more doses ofbendamustine.

A further aspect of the invention includes kits containing lyophilizedbendamustine or a pharmaceutically acceptable salt thereof in a firstcontainer or vial; and, in a second container, a sufficient amount of apharmaceutically acceptable fluid such as those described herein, i.e.one of the following:

-   -   A) i) PEG, PG or mixtures thereof; and        -   ii) a stabilizing amount of an antioxidant;    -   B) i) one or more of PG, ethanol, PEG, glycofurol and benzyl        alcohol; and        -   ii) a stabilizing amount of a chloride salt; or    -   C) DMSO.

For purposes of this embodiment, the amount of fluid which is sufficientis an amount which allows the bendamustine to be dissolved or dispersedto a degree which renders the liquid composition ready for use.

As will be appreciated by those of ordinary skill, the kit will containother pharmaceutically necessary materials for storing and/oradministering the drug, including instructions for storage and use,additional diluents, if desired, etc.

EXAMPLES

The following examples serve to provide further appreciation of theinvention but are not meant in any way to restrict the effective scopeof the invention.

Example 1

Bendamustine-containing compositions were prepared by dissolvingbendamustine HCl to a concentration of 10 mg/ml in one of ethanol,propylene glycol and benzyl alcohol as indicated in Table 1 below. 215mg/ml of choline chloride was added in half of the samples as a sourceof soluble chloride ions. The samples were maintained at 40° C. andanalyzed periodically for drug content and total impurities. The resultsobtained are presented in Table 1.

TABLE 1 Stability of Bendamustine HCl BDM % Total Formulation Temp Timemg/ml Impurities BDM—10 mg/mL Initial 10.43 0.27 Choline chloride— 40°C. 48 hrs 10.48 1.27 215 mg/mL 7 day 10.26 2.11 Ethanol qs to 1 mLBDM—10 mg/mL Initial 10.55 0.27 Ethanol qs to 1 mL 40° C. 48 hrs 10.302.39 7 day  9.55 6.66 BDM—10 mg/mL Initial  9.99 0.21 Choline chloride—40° C. 48 hrs  9.95 0.60 215 mg/mL 7 day  9.43 2.31 Propylene glycol qsto 1 mL BDM—10 mg/mL Initial  9.68 0.21 Propylene glycol qs 40° C. 48hrs  9.45 0.88 to 1 mL 7 day  9.00 3.44 BDM—10 mg/mL Initial  9.95 1.19Choline Chloride— 40° C. 48 hrs  9.89 3.51 215 mg/mL 7 day  8.97 4.24Benzyl alcohol qs to 1 mL BDM—10 mg/mL Initial  9.52 0.33 Benzyl alcoholqs 40° C. 48 hrs  8.67 4.18 to 1 mL 7 day  7.49 7.84 Note: In Table 1the total % impurities include total contributions from peaks at variousRRTs.

As shown in Table 1, the bendamustine formulations are very stable insolutions containing solvent and chloride salt. Table 1 shows thatbendamustine, when dissolved at a concentration of about 10 mg/mL, in apharmaceutically acceptable fluid, such as ethanol and propylene glycol,and containing a stabilizing amount of a chloride salt, such as cholinechloride, had less than about 5% after at least 7 days storage at 40° C.

The data presented in Table 1 translates to bendamustine-containingcompositions including a pharmaceutically acceptable fluid and astabilizing amount of a chloride salt having a shelf life of at leastabout 15 months at 5° C. and 25° C.

The sample including ethanol alone exhibited more than 6.5 totaldegradants after 7 days storage at 40° C. The sample including benzylalcohol alone exhibited more than 7.5% total degradants after 7 daysstorage at 40° C. Bendamustine-containing compositions with such highlevels of degradation would not be suitable for long-term storage.

Example 2

Bendamustine-containing compositions were prepared by dissolvingbendamustine HCl to a concentration of 10 mg/ml in DMSO. The sampleswere maintained at 40° C. and analyzed periodically for drug content andimpurity profile. The results obtained are presented in Table 2.

TABLE 2 Stability of Bendamustine HCl in DMSO Content % TotalFormulation Temp Time (mg/mL) Imp BDM—10 mg/mL Initial 10.2 0.23 DMSO qsto 1 mL 40° C. 48 hrs 9.80 0.30 1 week 10.0 0.56 Note: In Table 2 thetotal % impurities include total contributions from peaks at variousRRTs.

Table 2 shows that bendamustine, when dissolved in DMSO, hadsubstantially no increase in total degradants. The data presented inTable 2 translates to bendamustine-containing compositions includingDMSO having a shelf life of at least about 15 months at 5° C. and 25° C.In fact, such compositions are expected to have long term stability forperiods beyond 15 months, i.e. up to 2 years or greater.

Example 3

Bendamustine-containing compositions were prepared by dissolvingbendamustine HCl to a concentration of 20 mg/ml in polyethylene glycol400 and 5 mg/ml of lipoic acid was added as a stabilizing antioxidant asindicated in Table 3 below. The samples were maintained at 40° C. or 25°C. and analyzed after 15 days for drug content and impurities. Theresults obtained are presented in Table 3.

TABLE 3 Stability of Bendamustine (20 mg/ml) in PEG 400 and AntioxidantsTime % Imp % Total Antioxidant T ° C. days % Initial RRT 0.58 Imps None25 15 97.6 2.08 2.28 40 15 56.3 2.17 41.9 Lipoic Acid 25 15 98.5 <LD0.23 5 mg/ml 40 15 97.5 0.33 0.53 <LD = Below Level of Detection

As shown in Table 3, bendamustine, when dissolved in a pharmaceuticallyacceptable fluid, such as polyethylene glycol, in the presence of astabilizing amount of an antioxidant, such as lipoic acid, hadsubstantially no increase in total degradants after a period of 15 days.The data presented in Table 3 translates to bendamustine-containingcompositions including a pharmaceutically acceptable fluid and astabilizing amount of an antioxidant having a shelf life of at leastabout 15 months at 5° C. and 25° C.

The sample including PEG alone, on the other hand, which did not containan antioxidant, did not exhibit stabilizing effects at 40° C. Thissample had more than 40% more total impurities than the sample includinglipoic acid. Bendamustine-containing compositions with such high levelsof total impurities would not be suitable for long-term storage.

Example 4

Bendamustine-containing compositions were prepared by dissolvingbendamustine HCl to a concentration of 50 mg/ml in 90% polyethyleneglycol 400 and 10% propylene glycol. 5 mg/ml of thioglycerol, α-lipoicacid or dihydrolipoic acid was added as a stabilizing antioxidant asindicated in Table 4 below. The samples were maintained at 40° C. andanalyzed after 15 days or one month for drug content and impurityprofile as indicated in Table 4 below. The results obtained arepresented in Table 4.

TABLE 4 Stability of Bendamustine (50 mg/ml) in 90% PEG 400, 10%Propylene Glycol and Antioxidant % Impurities RRT % T Content % HP1 PGester Total Antioxidant (° C.) Time (mg/mL) Initial 0.59 1.10 ImpsThioglycerol 40 initial 48.8 100 <LD <LD 0 40 1 month 48.5 99.4 0.060.20 0.71 α-lipoic acid 40 initial 49 100 <LD <LD 0 40 15 days 48.8 99.60.19 0.13 0.32 40 1 month 48.7 99.4 0.34 0.26 0.79 Dihydrolipoic 40initial 49.3 100 <LD <LD 0 acid 40 1 month 47.7 97.4 0.63 0.12 1.84 <LD= Below Level of Detection

As shown in Table 4, bendamustine, when dissolved in a pharmaceuticallyacceptable fluid, such as a combination of polyethylene glycol andpropylene glycol, in the presence of a stabilizing amount of anantioxidant, such as thioglycerol, α-lipoic acid or dihydrolipoic acid,had substantially no increase in total degradants after a period of 1month. This data supports the position that bendamustine-containingcompositions according to the invention have a shelf life of at leastabout 2 years when stored at temperatures between 5° C. and 25° C.

Example 5

Bendamustine-containing compositions were prepared by dissolvingbendamustine HCl to a concentration of 50 mg/ml in a mixture ofpolyethylene glycol 400 and propylene glycol as indicated in Table 5below. 5 mg/ml of lipoic acid was added as a stabilizing antioxidant.The samples were maintained at 40° C., 25° C. and 5° C. and analyzedafter 1 week, 15 days or one month for drug content and impurity profileas indicated in Table 5 below. The results obtained are presented inTable 5.

TABLE 5 Stability of Bendamustine (50 mg/ml) and Lipoic Acid (5 mg/ml)in PEG400 and Propylene glycol % Area of degradants % Time Content % ofHP1 PG ester PG ester Total Formulation Temp. Period (mg/mL) Initial0.58 1.10 1.13 Imp. BDM - Initial 49.6 100 BDL BDL BDL 0.18 50 mg/mL 40°C. 1 W 49.0 98.8 0.05 0.13 BDL 0.38 Lipoic acid - 15 d 48.3 97.4 0.080.26 BDL 0.55 5 mg/mL 1 M 48.0 96.8 0.11 0.43 0.13 1.03 PEG 25° C. 15 d49.6 100.0 BDL 0.10 BDL 0.30 400:PG 1 M 48.4 97.6 0.05 0.19 BDL 0.43(75:25) qs  5° C. 1 M 49.6 100.0 BDL 0.07 BDL 0.27 to 1 mL BDM - Initial50.2 100 BDL BDL BDL 0.21 50 mg/mL 40° C. 1 W 49.9 99.4 BDL 0.15 BDL0.30 Lipoic acid - 15 d 49.1 97.8 0.06 0.35 BDL 0.73 5 mg/mL 1 M 49.097.6 0.09 0.90 0.25 1.82 PEG 25° C. 15 d 49.9 99.4 BDL 0.12 BDL 0.32400:PG 1 M 49.7 99.0 BDL 0.25 BDL 0.59 (50:50) qs  5° C. 1 M 50.0 99.6BDL 0.11 BDL 0.33 to 1 mL BDM - Initial 50.8 100 BDL BDL BDL 0.21 50mg/mL 40° C. 1 W 50.4 99.2 BDL 0.11 BDL 0.30 Lipoic acid - 15 d 49.797.8 0.07 0.17 BDL 0.43 5 mg/mL 1 M 49.7 97.8 0.13 0.27 0.09 0.84 PEG25° C. 15 d 50.8 100.0 BDL 0.10 BDL 0.26 400:PG 1 M 50.8 100.0 0.05 0.14BDL 0.39 (90:10) qs  5° C. 1 M 50.8 100.0 BDL 0.06 BDL 0.34 to 1 mL BDL= Below Detectable Limit

As shown in Table 5, bendamustine, when dissolved in certain mixtures ofpolyethylene glycol and propylene glycol and a stabilizing amount oflipoic acid, had substantially no increase in total degradants after aperiod of 1 month. The data presented in Table 5 translates tobendamustine-containing compositions having a shelf life of at leastabout 2 years when stored at temperatures between 5° C. and at 25° C.

Example 6

Bendamustine-containing compositions were prepared by dissolvingbendamustine HCl to a concentration of 50 mg/ml in 90% polyethyleneglycol 400 and 10% propylene glycol and α-lipoic acid was added as astabilizing antioxidant as indicated in Table 6 below. The samples weremaintained at 40° C., 25° C. and 5° C. and analyzed for drug content andimpurity profile as indicated in Table 6 below. The results obtained arepresented in Table 6.

TABLE 6 Stability of Bendamustine in 90% PEG 400, 10% PG and α-lipoicacid % Time Amt. % of % Area of degradants Total Formulation Temp Per.mg/ml Initial 0.59 1.10 1.13 1.15 1.17 1.20 1.22 1.30 Imp. BDM - Initial51.0 100 0.20 0.06 <LD <LD <LD <LD <LD <LD 0.26 50 mg/mL 40° C. 1 M 50.599.0 0.21 0.31 0.13 0.07 0.13 0.10 <LD <LD 0.95 α-lipoic 2 M 49.7 97.50.22 0.71 0.28 0.14 0.12 0.21 0.12 <LD 2.02 acid - 3 M 48.7 95.5 0.221.01 0.45 0.21 0.14 0.37 0.16 0.05 2.96 10 mg/mL 25° C. 3 M 50.5 99.00.20 0.36 0.07 <LD <LD 0.10 <LD <LD 0.73 PEG 6 M 50.4 98.8 0.22 0.600.17 0.06 0.06 0.09 0.10 0.08 1.44 400:PG  5° C. 6 M 50.9 99.8 0.16 0.05<LD <LD <LD <LD <LD <LD 0.21 (90:10) qs 12 M  50.6 99.2 0.20 0.18 <LD<LD <LD <LD <LD <LD 0.38 to 1 mL BDM - Initial 50.3 100 0.18 <LD <LD <LD<LD <LD <LD <LD 0.18 50 mg/mL 40° C. 1 M 50.0 99.4 0.19 0.32 0.08 0.060.08 0.06 0.06 <LD 0.85 α-lipoic 2 M 49.8 99.0 0.19 0.65 0.21 0.12 0.130.23 0.14 0.06 1.85 acid - 3 M 49.5 98.4 0.15 0.89 0.37 0.17 0.13 0.320.10 <LD 2.40 15 mg/mL 6 M 47.0 93.4 0.20 1.76 0.66 0.19 0.31 0.47 0.330.17 4.93 PEG 25° C. 3 M 50.0 99.4 0.20 0.35 0.08 <LD <LD <LD 0.11 <LD0.79 400:PG 6 M 49.5 98.4 0.19 0.58 0.15 0.06 0.07 0.09 0.08 0.10 1.38(90:10) qs  5° C. 6 M 50.3 100 0.17 0.06 <LD <LD <LD <LD <LD <LD 0.23 to1 mL 12 M  50.2 99.8 0.19 0.15 <LD <LD <LD <LD <LD <LD 0.34 <LD = BelowLevel of Detection

The data reported in Table 6 along with the data in Table 5 demonstratesthat bendamustine solutions are stable when dissolved in mixtures of PEGand PG and 5-15 mg/mL α-lipoic acid. As shown in Table 6, bendamustine,when dissolved in combinations of polyethylene glycol and propyleneglycol, in the presence of a stabilizing amount of lipoic acid, had lessthan 3% increase in total degradants after a period of 3 months at 40°C. Additionally, the same compounds had substantially no increase intotal degradants after a period of 6-12 months at 5° C. and 25° C. Thedata corresponds to bendamustine solutions being stable under ambient orrefrigerated storage conditions for well in excess of 2 years, and thuslong term stable.

Example 7

Bendamustine-containing compositions were prepared by dissolvingbendamustine HCl to a concentration of 50 mg/ml in 90% polyethyleneglycol 400 and 10% propylene glycol. 2.5 mg/ml of thioglycerol was addedas an antioxidizing agent. The samples were maintained at 40° C. and 25°C. and analyzed for drug content and impurity profile as indicated inTable 7 below. The results obtained are presented in Table 7.

TABLE 7 Stability of Bendamustine in 90% PEG 400, 10% PG andThioglycerol % Time Amt % of RRTs of degradants Total Formulation TempPer. mg/ml Initial 0.15 0.37 1.10 1.13 1.15 1.17 1.18 1.20 1.22 Imp.BDM - Initial 50.3 100 BDL BDL BDL BDL BDL BDL BDL BDL BDL 0.00 50 mg/mL40° C. 15 d   50.2 99.8 BDL BDL 0.18 BDL BDL BDL 0.05 0.08 BDL 0.31Thioglycerol 1 M 49.9 99.2 BDL 0.12 0.32 0.07 BDL BDL 0.09 0.08 BDL 0.752.5 mg/mL 2 M 49.1 97.6 BDL 0.18 0.56 0.24 0.09 0.17 0.19 0.12 0.11 1.76PEG 3 M 48.8 97.0 BDL 0.23 0.85 0.34 0.16 0.30 0.34 0.29 0.19 2.94400:PG 25° C. 3 M 49.9 99.2 0.06 0.12 0.23 0.07 BDL 0.06 0.07 0.06 BDL0.67 (90:10) qs 6 M 49.3 98.0 BDL 0.23 0.53 0.22 0.11 BDL 0.21 0.22 0.202.07 to 1 mL BDL = Below Detectable Limit

The stability is similar to that of α-lipoic acid samples in Example 6above. As shown in Table 7, bendamustine, when dissolved in acombination of polyethylene glycol and propylene glycol, and astabilizing amount of thioglycerol, had less than 3% increase in totaldegradants after a period of 3 months at 40° C. Additionally, the samecompounds had substantially no increase in total degradants after aperiod of 6 months at 25° C. The data reported supports the conclusionthat these bendamustine solutions are stable under ambient orrefrigerated storage conditions for about 2 years.

Example 8

Bendamustine-containing compositions were prepared by dissolvingbendamustine HCl to a concentration of 50 mg/ml in 85% PEG 400 and 15%PG in the presence of 5 mg/ml of thioglycerol. The samples weremaintained at 40° C. and 25° C. and analyzed for drug content andimpurity profile as indicated in Table 8 below. The results obtained arepresented in Table 8.

TABLE 8 Stability of Bendamustine in 85% PEG 400, 15% PG andThioglycerol % Time Content % of Total Formulation Temp. Period (mg/mL)Initial Imp. BDM—50 mg/mL Initial 51.5 100 0.12 Thioglycerol—5 mg/mL 40°C. 1 M 50.4 97.9 1.18 PEG 400:PG (85:15) qs to 25° C. 1 M 51.4 99.8 0.411 mL 3 M 50.4 97.9 1.21  5° C. 3 M 51.0 99.0 0.26

The stability is similar to that of thioglycerol samples in Example 7above. As reported in Table 8, total impurities did not exceed 2% at 40°C. or 25° C. storage over one month, or at 25° C. and 5° C. storageafter three months. The data reported in Table 8 supports the conclusionthat these bendamustine solutions are stable under ambient orrefrigerated storage conditions for at least about 2 years if notlonger.

We claim:
 1. A ready to use liquid bendamustine-containing compositioncomprising bendamustine, or a pharmaceutically acceptable salt thereof,wherein the bendamustine concentration in the composition is from about10 mg/mL to about 100 mg/mL; polyethylene glycol; and a stabilizingamount of an antioxidant; the composition having less than about 5% peakarea response of total impurities resulting from the degradation of thebendamustine, as determined by HPLC as a wavelength of 223 nm after atleast 15 months at a temperature of from about 5° C. to about 25° C. 2.The ready to use liquid bendamustine-containing composition of claim 1,wherein the antioxidant is lipoic acid, thioglycerol, propyl gallate,methionine, cysteine, a metabisulfite, sodium formaldehyde sulfoxylate,a phenol-containing aromatic compound, a phenol-containing aliphaticcompound, dihydrolipoic acid, or a mixture thereof.
 3. The ready to useliquid bendamustine-containing composition of claim 1, having less thanabout 5% peak area response of total impurities resulting from thedegradation of the bendamustine, as determined by HPLC as a wavelengthof 223 nm after at least 15 months at a temperature of about 5° C. 4.The ready to use liquid bendamustine-containing composition of claim 1,having less than about 5% peak area response of total impuritiesresulting from the degradation of the bendamustine, as determined byHPLC as a wavelength of 223 nm after at least 15 months at a temperatureof about 25° C.
 5. The ready to use liquid bendamustine-containingcomposition of claim 1, wherein the bendamustine concentration is fromabout 20 mg/mL to about 60 mg/mL.
 6. The ready to use liquidbendamustine-containing composition of claim 1, wherein the bendamustineconcentration is about 25 mg/mL.
 7. The ready to use liquidbendamustine-containing composition of claim 1, comprising bendamustinehydrochloride.
 8. A method of treating cancer in a mammal, comprisingadministering an effective amount of the ready to use liquidbendamustine-containing composition of claim 1 to the mammal.
 9. Themethod of claim 8, wherein the cancer is leukemia.
 10. The method ofclaim 8, wherein the cancer is Hodgkin's disease.
 11. The method ofclaim 8, wherein the antioxidant is lipoic acid, thioglycerol, propylgallate, methionine, cysteine, a metabisulfite, sodium formaldehydesulfoxylate, a phenol-containing aromatic compound, a phenol-containingaliphatic compound, dihydrolipoic acid, or a mixture thereof.
 12. Themethod of claim 8, wherein the ready to use liquidbendamustine-containing composition has less than about 5% peak arearesponse of total impurities resulting from the degradation of thebendamustine, as determined by HPLC as a wavelength of 223 nm after atleast 15 months at a temperature of about 5° C.
 13. The method of claim8, wherein the ready to use liquid bendamustine-containing compositionhas less than about 5% peak area response of total impurities resultingfrom the degradation of the bendamustine, as determined by HPLC as awavelength of 223 nm after at least 15 months at a temperature of about25° C.
 14. The method of claim 8, wherein the bendamustine concentrationin the ready to use liquid bendamustine-containing composition is fromabout 20 mg/mL to about 60 mg/mL.
 15. The method of claim 8, wherein thebendamustine concentration in the ready to use liquidbendamustine-containing composition is about 25 mg/mL.
 16. The method ofclaim 8, wherein the ready to use liquid bendamustine-containingcomposition comprises bendamustine hydrochloride.